Ages of HP Characters

[catlady_de_los_angeles]

No: HPFGUIDX 32908

http://www.scholastic.com/harrypotter/author/transcript2.htm says:
"Q: How old is old in the wizarding world, and how old are Professors 
Dumbledore and McGonagall?
 A: Dumbledore is a hundred and fifty, and Professor McGonagall is a 
sprightly seventy. Wizards have a much longer life expectancy than 
Muggles. (Harry hasn't found out about that yet.)"

http://www.comicrelief.com/harrysbooks/pages/transcript.shtml says:
"Q: How old are Professor Dumbledore and Professor Snape? 
 A: Dumbledore's about 150 years old... wizards have a longer life 
expectancy than us Muggles, Snape's 35 or 6." 

I figured that maybe wizarding folk age at the same rate as Muggles 
for the first 20 (or 21, which is a magical number) years, and then
at half the rate of Muggles, trying the following computations:

Dumbledore is 150. # 150 - 20 = 130. # 130 / 2 = 65. # 65 + 20 = 85.
85 with long white beard and hair and starting to look worn and 
tired sounds plausible enough, I guess 150 years old is the wizard 
equivalent of 85 Muggle years old.

McGonagall is 70. # 70 - 20 = 50. # 50 / 2 = 25. # 25 + 20 = 45.
45 and her hair is still black is plausible enough, and she looks 
younger than I would have thought in JKR's own sketch of her (posted 
in the Photos Section by Muridae (anony-Mice?)). Thus 70 years old is 
the wizarding equivalent of 45 Muggle years old... 

Which suggests that some witches can still bear children at age 70.

Arthur and Molly Weasley appear to be in their (Muggle equivalent) 
late 40s. Call it 50. # 50 - 20 = 30. # 30 * 2 = 60. # 60 + 20 = 80.
If they are 80 years old, there is NO PROBLEM with Molly reminiscing 
of the gamekeeper before Hagrid, a man named Ogg. They would have 
left school the year before Hagrid even entered, let alone was 
expelled.

HOWEVER, 
in Tom Riddle's diary,
Dumbledore was 100. # 100 - 20 = 80. # 80 / 2 = 40 # 40 + 20 = 60.
And I have trouble believing that Dumbledore in Tom Riddle's Diary 
had a Muggle equivalent age a day over 50, and it was surely closer 
to 40. The hair and beard were (as Brooks said in the YahooClubs 
HP4GU post which inspired the original of this essay) described as 
'auburn', not 'auburn at the  bottom fading to white at the roots' or 
'faded auburn streaked with white', and there is no indication of 
worry lines on forehead or smile lines beside eyes. Can someone 
please explain this away for me?

Minerva COULD have been a 7th year student in 1945 (as in a fanfic 
mentioned in that ghost-club's discussion). JKR's statement that she 
'is' 70 depends on 'what the meaning of "is" is' -- Minerva was 70 at 
the time of Book 1 (1991-2 school year) OR  at the time of Book 4 
(1994-5) (interview was for Book 4's book release publicity tour) OR 
at the time of the interview (2000) OR 'now' (2002).

So I chose an interpretation of 'is' which makes her the same age as 
Hagrid, a third year student in 1942-43, thus a seventh year student 
in 1946-47... That is, born seventy years some months before the day 
of that interview. 

JKR said Snape 'is' thirty-five or thirty-six. As I am married to my 
conviction that the Marauders and Snape are the same age as me, that 
is, born in 1957-58, I interpreted that 'is' to mean that he was 36 
years and several months at the moment GoF began in summer of '94. 

However, that damn plaque in the movie messes it up. James Potter, 
Seeker, 1972. In my world, James would have been a third-year in '72. 
If the plaque stands for winning the Quidditch Cup, therefore Gryff 
won it when James was third-year, then Gryff surely won it in other 
years that James was on the team. And if the plaque is Player of the 
Year and he won it as a third-year, he should have won it that much 
more when he was older, more experienced, and bigger and stronger.

DO YOU THINK THE PLAQUE COULD HAVE BEEN Rookie of the Year? Do you 
think the great James Potter might not have made it onto the first 
string until his third year, or that he was really Class of '75 not 
'76 (and won Rookie of the Year as a second-year)? Lexicon Steve says 
the movie is not canon, but I want that plaque to be real because I 
want James to have been Seeker not Chaser.